/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 * KOML.java
 * Copyright (C) 2004 University of Waikato, Hamilton, New Zealand
 */

package weka.core.xml;

import weka.core.RevisionHandler;
import weka.core.RevisionUtils;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * This class is a helper class for XML serialization using <a
 * href="http://koala.ilog.fr/XML/serialization/" target="_blank">KOML</a> .
 * KOML does not need to be present, since the class-calls are done generically
 * via Reflection.
 * 
 * @author FracPete (fracpete at waikato dot ac dot nz)
 * @version $Revision 1.0$
 */
public class KOML implements RevisionHandler {

	/**
	 * indicates whether <a href="http://koala.ilog.fr/XML/serialization/"
	 * target="_blank">KOML</a> (Koala Object Markup Language) is present
	 */
	protected static boolean m_Present = false;

	/** the extension for KOML files (including '.') */
	public final static String FILE_EXTENSION = ".koml";

	/** check for KOML statically (needs only to be done once) */
	static {
		checkForKOML();
	}

	/**
	 * checks whether the KOML is present in the class path
	 */
	private static void checkForKOML() {
		try {
			Class.forName("fr.dyade.koala.xml.koml.KOMLSerializer");
			m_Present = true;
		} catch (Exception e) {
			m_Present = false;
		}
	}

	/**
	 * returns whether KOML is present or not, i.e. whether the classes are in
	 * the classpath or not
	 * 
	 * @return whether KOML is available
	 */
	public static boolean isPresent() {
		return m_Present;
	}

	/**
	 * reads the XML-serialized object from the given file
	 * 
	 * @param filename
	 *            the file to deserialize the object from
	 * @return the deserialized object
	 * @throws Exception
	 *             if something goes wrong while reading from the file
	 */
	public static Object read(String filename) throws Exception {
		return read(new FileInputStream(filename));
	}

	/**
	 * reads the XML-serialized object from the given file
	 * 
	 * @param file
	 *            the file to deserialize the object from
	 * @return the deserialized object
	 * @throws Exception
	 *             if something goes wrong while reading from the file
	 */
	public static Object read(File file) throws Exception {
		return read(new FileInputStream(file));
	}

	/**
	 * reads the XML-serialized object from a stream
	 * 
	 * @param stream
	 *            the stream to deserialize the object from
	 * @return the deserialized object
	 * @throws Exception
	 *             if something goes wrong while reading from the stream
	 */
	public static Object read(InputStream stream) throws Exception {
		Class komlClass;
		Class[] komlClassArgs;
		Object[] komlArgs;
		java.lang.reflect.Constructor constructor;
		Object koml;
		java.lang.reflect.Method methodRead;
		java.lang.reflect.Method methodClose;
		Class[] readArgsClasses;
		Class[] closeArgsClasses;
		Object[] readArgs;
		Object[] closeArgs;
		Object result;

		result = null;

		// get Deserializer
		komlClass = Class.forName("fr.dyade.koala.xml.koml.KOMLDeserializer");
		komlClassArgs = new Class[2];
		komlClassArgs[0] = java.io.InputStream.class;
		komlClassArgs[1] = Boolean.TYPE;
		komlArgs = new Object[2];
		komlArgs[0] = stream;
		komlArgs[1] = new Boolean(false);
		constructor = komlClass.getConstructor(komlClassArgs);
		koml = constructor.newInstance(komlArgs);
		readArgsClasses = new Class[0];
		methodRead = komlClass.getMethod("readObject", readArgsClasses);
		readArgs = new Object[0];
		closeArgsClasses = new Class[0];
		methodClose = komlClass.getMethod("close", closeArgsClasses);
		closeArgs = new Object[0];

		// execute it
		try {
			result = methodRead.invoke(koml, readArgs);
		} catch (Exception e) {
			result = null;
		} finally {
			methodClose.invoke(koml, closeArgs);
		}

		return result;
	}

	/**
	 * writes the XML-serialized object to the given file
	 * 
	 * @param filename
	 *            the file to serialize the object to
	 * @param o
	 *            the object to write to the file
	 * @return whether writing was successful or not
	 * @throws Exception
	 *             if something goes wrong while writing to the file
	 */
	public static boolean write(String filename, Object o) throws Exception {
		return write(new FileOutputStream(filename), o);
	}

	/**
	 * write the XML-serialized object to the given file
	 * 
	 * @param file
	 *            the file to serialize the object to
	 * @param o
	 *            the object to write to the file
	 * @return whether writing was successful or not
	 * @throws Exception
	 *             if something goes wrong while writing to the file
	 */
	public static boolean write(File file, Object o) throws Exception {
		return write(new FileOutputStream(file), o);
	}

	/**
	 * writes the XML-serialized object to a stream
	 * 
	 * @param stream
	 *            the stream to serialize the object to
	 * @param o
	 *            the object to write to the stream
	 * @return whether writing was successful or not
	 * @throws Exception
	 *             if something goes wrong while writing to the stream
	 */
	public static boolean write(OutputStream stream, Object o) throws Exception {
		Class komlClass;
		Class[] komlClassArgs;
		Object[] komlArgs;
		java.lang.reflect.Constructor constructor;
		Object koml;
		java.lang.reflect.Method methodAdd;
		java.lang.reflect.Method methodClose;
		Class[] addArgsClasses;
		Class[] closeArgsClasses;
		Object[] addArgs;
		Object[] closeArgs;
		boolean result;

		result = false;

		// get Deserializer
		komlClass = Class.forName("fr.dyade.koala.xml.koml.KOMLSerializer");
		komlClassArgs = new Class[2];
		komlClassArgs[0] = java.io.OutputStream.class;
		komlClassArgs[1] = Boolean.TYPE;
		komlArgs = new Object[2];
		komlArgs[0] = stream;
		komlArgs[1] = new Boolean(false);
		constructor = komlClass.getConstructor(komlClassArgs);
		koml = constructor.newInstance(komlArgs);
		addArgsClasses = new Class[1];
		addArgsClasses[0] = Object.class;
		methodAdd = komlClass.getMethod("addObject", addArgsClasses);
		addArgs = new Object[1];
		addArgs[0] = o;
		closeArgsClasses = new Class[0];
		methodClose = komlClass.getMethod("close", closeArgsClasses);
		closeArgs = new Object[0];

		// execute it
		try {
			methodAdd.invoke(koml, addArgs);
			result = true;
		} catch (Exception e) {
			result = false;
		} finally {
			methodClose.invoke(koml, closeArgs);
		}

		return result;
	}

	/**
	 * Returns the revision string.
	 * 
	 * @return the revision
	 */
	public String getRevision() {
		return RevisionUtils.extract("$Revision: 1.4 $");
	}
}
